Display and display system for medical use

ABSTRACT

The medical display includes a display device of a matrix type having a resolution of 100 to 300 ppi to display a medical image and at least one anti-reflection layer on a side of a front surface of said display device. The medical display system includes the medical display and a luminance meter measuring luminance. The anti-reflection layer has an average specular reflectivity of 0.5% or less at an incident angle of 5° in a wavelength range of 450 to 650 nm, receives light from a CIE standard light source D65 at an incident angle of 5° in a wavelength range of 380 to 780 nm to reflect the light as regular reflection light whose color falls within a range of −7≦a*≦7 and −10≦b*≦10 in terms of a* and b* values of CIE 1976 L*a*b* color space, and is placed on a surface whose flatness is defined by an arithmetic average height Ra and a maximum height Rz according to JIS B 0601-2001, with Ra set at 0.02 μm or less and Rz set at 0.04 μm or less.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a medical display and a medical displaysystem using the display. In particular, the present invention relatesto a medical display provided with an anti-reflection film which is flator has a given degree of flatness, in other words, which does not havean anti-glare property, and a medical display system for displaying animage on the medical display.

2. Description of the Related Art

A diagnostic image taken and processed by a medical measurement (imagepickup) apparatus such as an MRI, a CT scanner, a DSA apparatus, an FCR(Fuji computed radiography) or other CR apparatus, a mammographyapparatus, or a digital X-ray radiography (DR) apparatus, is usuallyrecorded on a light-transmissive image recording film such as an X-rayfilm or a photosensitive film, and reproduced as a light-transmissiveimage. The film on which the diagnostic image is reproduced is set in alight source apparatus called a film viewer and is illuminated from theback. The backlit diagnostic image on the film is observed as atransmission image for diagnosis.

An alternative has become available in recent years and a diagnosticimage taken by a medical measurement apparatus can now be displayed fordiagnosis on various image display devices (electronic film viewer) suchas a liquid crystal display device (LCD), a plasma display panel (PDP),an electroluminescence display (ELD, in particular, organic ELD), or aCRT (cathode ray tube) display device.

In an image display device (display) as given above, its display screenhas an anti-glare (AG) property in order to avoid surface reflection onthe display screen and to prevent an image displayed on the screen fromglaring for improved visibility of the display screen. The AG propertyis obtained by making the front or rear surface of the material of thedisplay screen, for example, a glass substrate or a polarization plate,irregular and then matting the front and rear surfaces of the substrateor the polarization plate through application of an application solutionthat contains matte particles. Alternatively, the AG property isacquired by forming transparent films on the front and rear surfaces ofa substrate or a polarization plate and making the surfaces of thetransparent films irregular through embossing or other method (See JP2000-275404 A).

Giving the AG property to a display screen (polarization plate) of thedisplay is effective against reflection light of an observer or anexternal object on the display screen.

On the other hand, the vividness and sharpness of an image displayed aredegraded because of the AG property, resulting in a blurred image. Also,glaring becomes conspicuous in medical displays of 100 to 300 ppi (pixelper inch), in particular, LCDs having a 200 ppi or higher resolutionmatrix structure for interpretation of a mammographic image in whichminute calcification or the like has to be interpreted. If the medicaldisplay in question is a monochrome display, image disturbances areparticularly noticeable, and an image is shifted in the front-to-backdirection due to the AG property, thus giving a ‘double vision’ look tothe image. The image disturbances cause an eye strain and presentdifficulties in interpreting the image.

In addition, the AG property makes the display screen reflect light fromthe surroundings at an increased diffuse reflectance. The screentherefore assumes a whitish appearance, causing dark areas of adisplayed image to look protruded and lowering contrast. A medical imagegenerally has a wide dynamic range of shades, so that lowering ofcontrast presents a great deterrent in making a diagnosis.

A transmission image on a film to be interpreted for diagnosis by aconventional film viewer shows a slight difference depending on theluminance of the film viewer used and observation environments, but isbasically the same. In contrast, an image displayed on a displayfluctuates when displayed on a different type of display, or when thedisplay undergoes a change in state or a change with time, or when thereare other factors. The fluctuation could cause a false diagnosis.Therefore, in making a diagnosis from interpretation of an imagedisplayed on a display, the display has to be kept in a given state tokeep the displayed image in a given, proper state. However, even whenthe state of a displayed image is kept constant, the appearance of thedisplayed image is varied depending on observation environments.

For that reason, DICOM (Digital Imaging and Communication in Medicine, astandard for transmission of medical image data, waveform data, and thelike) prescribes that a diagnostic image can be displayed on a displayonly after performing gradation correction using GSDF (GrayscaleStandard Display Function). The standard also prescribes that gradationcorrection should be performed by taking into account not only theluminance of the display but also observation environments including theluminance of peripheral light. However, gradation correction inconsideration of the luminance of peripheral light narrows the dynamicrange of a medical image displayed when the contrast is lowered, andthis works against the fact that a wide dynamic range of shades isrequired in a medical image.

On the other hand, when a display screen (polarization plate) of adisplay does not have the AG property (when the display screen isuntreated), the display screen is large in specular reflectivity (about4%) and therefore has less ability to avoid reflection of light of aviewer or an external object on the screen while an image obtainedresembles a transmission image on a film which is vivid and sharp andwhich has no glare. In a medical monochrome LCD for interpreting subtleshades, to obtain an image resembling a transmission image on a filmwhich is vivid and sharp and which has no glare takes precedence andtherefore the display screen of the display is stripped of AG property.Reflection of light of a viewer or an external object on a displayscreen can be reduced by shutting out peripheral light, but this is notenough to completely eliminate reflection on the display screen becauselight of the display screen itself is reflected by the viewer of thedisplay screen. In clinical environment, in particular, viewers usuallywear lab coats and that much more likely to cause reflection on thescreen.

This problem could be solved by giving a display screen of a display ananti-reflection (AR) property.

An anti-reflection (AR) film that has conventionally been used to impartthe AR property is a multilayer film having layers of transparent thinfilms of metal oxides. Plural transparent thin films are used in orderto prevent reflection of light in as wide a wavelength range as possiblewithin the visible light range. Such transparent thin films of metaloxides are formed by evaporation, for example, chemical vapor deposition(CVD) and physical vapor deposition (PVD). Vacuum evaporation orsputtering which is one of physical vapor deposition methods isparticularly employed to form those films. In the evaporation methods,an AR film obtained is low in specular reflectivity (0.5% or less) andtherefore has an excellent ability to avoid reflection of light of aviewer or the surroundings on the display screen. However, the cost ishigh, and the original color of the displayed image is impaired bycoloring due to the AR film, which is a serious problem. To elaborate,an AR film formed by one of those evaporation methods to have an averagereflectivity of 0.5% or less, in particular, 0.4% or less, in awavelength range of 450 nm to 650 nm is excellent in avoiding reflectionon the display screen while the film has a poor reflectioncharacteristic on the long wavelength side and the short wavelength side(especially the short wavelength side), resulting in poor colorneutrality. Because of the poor color neutrality, light reflected by theAR film is heavily colored in reddish purple to bluish purple, and thusthe. display quality is degraded. One more problem in employingevaporation or sputtering is that the manufacture method produces ARfilms in batches and therefore is low in productivity while being highin cost.

Application is another conventional way to obtain the AR property, andan AR film can be created by applying inorganic particles or polymersonce or more to form a single layer or multiple layers. Application is alow-cost method because a large continuous area of a film can be formedby roll-to-roll. However, an AR film manufactured by application isabout 1 to 2% in specular reflectivity and the average reflectivityexceeds 1%, which presents a serious problem of insufficient AR ability.Although some conventional application methods have been successful inobtaining an average reflectivity of 0.5% or less, light reflected by anAR film that is formed by application is heavily colored in reddishpurple when the color of the reflected light is calculated from thereflection spectrum or when a real sample of the AR film is observedvisually. Accordingly, the display quality is degraded as is the casefor an AR film formed by evaporation. In addition, since the reflectedlight is colored heavily, a slight fluctuation in thickness of theanti-reflection layer leads to a color shift great enough to berecognized visually (see JP 11-6902 A).

For that reason, the AR property is not given to a display screen of amedical display for interpreting subtle shades, in particular, a medicalmonochrome display.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above-describedproblems of prior art, and an object of the present invention is toprovide a medical display capable of displaying, without an anti-glareproperty, at low cost, a film-like, high-quality, diagnostic image whichis free from reflection on the display screen and coloring by the use ofa high performance anti-reflection (AR) film which has no anti-glareproperty and which is successful in achieving at the same time loweringof specular reflectivity and reduction in color tint.

Another object of the present invention is to provide a medical displaysystem for enabling this medical display to stably display thediagnostic image.

In order to attain the objects described above, the first aspect of thepresent invention provides a medical display, comprising a displaydevice of a matrix type having a resolution of 100 to 300 ppi to displaya medical image, and at least one anti-reflection layer on a side of afront surface of the display device, wherein the anti-reflection layerhas an average specular reflectivity of 0.5% or less at an incidentangle of 5° in a wavelength range of 450 to 650 nm, the anti-reflectionlayer receives light from a CIE standard light source D65 at an incidentangle of 5° in a wavelength range of 380 to 780 nm to reflect the lightas regular reflection light whose color falls within a range of −7≦a*≦7and −10≦b*≦10 in terms of a* and b* values of CIE 1976 L*a*b* colorspace, and the anti-reflection layer is placed on a surface whoseflatness is defined by an arithmetic average height Ra and a maximumheight Rz according to JIS B 0601-2001, with Ra set at 0.02 μm or lessand Rz set at 0.04 μm or less.

Preferably, the anti-reflection layer in a form of an anti-reflectionfilm is formed on a support.

And, preferably, the anti-reflection film is spread over the frontsurface of the display device.

Further, preferably, a protective panel is attached to the front surfaceof the display device in a manner that puts a distance between theprotective panel and the front surface of the display device to avoidcontact, and one of the anti-reflection film and the anti-reflectionlayer is placed on each side of the protective panel.

Preferably, the anti-reflection film has a transparent support having arefractive index of n_(B), a hard coat layer having a refractive indexof n_(H) and being placed on the transparent support, and theanti-reflection layer being placed on the hard coat layer, wherein theanti-reflection layer practically has three sub-layers of differentrefractive indexes, with an intermediate refractive sub-layer beingclosest to the transparent support and having a refractive index of n1,a high refractive sub-layer following the intermediate refractivesub-layer and having a refractive index of n2, and a low refractivesub-layer being farthest to the transparent support and having arefractive index of n3, wherein the refractive indexes of the threesub-layers satisfy the following relations,n3<n_(B), n_(H)<n1<n2

wherein, at a design wavelength λ (500 nm), the intermediate refractivesub-layer, the high refractive sub-layer, and the low refractivesub-layer satisfy the following expressions (I), (II), and (III),respectively.λ/4×0.80<n1×d1<λ/4×1.00  (I)λ/2×0.75<n2×d2<λ/2×0.95  (II)λ/4×0.95<n3×d3<λ/4×1.05  (III)(where d1 represents a thickness (nm) of the intermediate refractivesub-layer, d2 represents a thickness (nm) of the high refractivesub-layer, and d3 represents a thickness (nm) of the low refractivesub-layer.)

Preferably, the anti-reflection layer is provided on the front surfaceof the display device.

And, preferably, the anti-reflection layer has such characteristics thatthe a* value and the b* value fulfill 0≦a*≦5 and −7≦b*≦0, respectively,and that the average specular reflectivity is 0.3% or less at theincident angle of 5° in the wavelength range of 450 nm to 650 nm.

Preferably, a size of a display screen on the front surface of thedisplay device is 18″ to 23″.

And, preferably, the display device is a monochrome display device.

And, preferably, a plane radiographic image obtained by CR (computedradiography) or using a flat panel sensor is displayed at a resolutionof 100 to 180 ppi.

Further, preferably, a mammographic image obtained by CR (computedradiography) or using a flat panel sensor is displayed at a resolutionof 180 to 300 ppi.

Moreover, in order to attain the objects described above, the secondaspect of the present invention provides a medical display system,comprising a medical display displaying a medical image, and a luminancemeter measuring luminance, wherein the medical display, comprising adisplay device of a matrix type having a resolution of 100 to 300 ppi;and at least one anti-reflection layer on a side of a front surface ofthe display device, wherein the anti-reflection layer has an averagespecular reflectivity of 0.5% or less at an incident angle of 5° in awavelength range of 450 to 650 nm, the anti-reflection layer receiveslight from a CIE standard light source D65 at an incident angle of 5° ina wavelength range of 380 to 780 nm to reflect the light as regularreflection light whose color falls within a range of −7≦a*≦7 and−10≦b*≦10 in terms of a* and b* values of CIE 1976 L*a*b* color space,and the anti-reflection layer is placed on a surface whose flatness isdefined by an arithmetic average height Ra and a maximum height Rzaccording to JIS B 0601-2001, with Ra set at 0.02 μm or less and Rz setat 0.04 μm or less, and wherein the medical display system has afunction of measuring surface reflection luminance when a power isturned off and display luminance when the power is turned on with theluminance meter, a function of judging measurement data and displayingjudgment results, a function of saving the measurement data and thejudgment results, and a function of correcting gradation based on themeasurement data.

Here, preferably, the luminance meter is connected online and has afunction of measuring the luminance in sync with display of a luminancemeasurement test pattern on a display screen of the display device.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic side view of a medical display according to anembodiment of the present invention;

FIG. 2 is a schematic sectional view of a liquid crystal display unit ofthe medical display according to the embodiment shown in FIG. 1;

FIG. 3 is a schematic sectional view showing a layer structure of a mainpart of the medical display according to the embodiment shown in FIG. 1;

FIG. 4 is a schematic sectional view showing the layer structure of ananti-reflection film in the medical display according to the embodimentshown in FIG. 3;

FIG. 5 is a schematic side view showing a layer structure of a main partof a medical display according to another embodiment of the presentinvention;

FIG. 6A is a schematic side view of a medical display according to stillanother embodiment of the present invention;

FIG. 6B is a schematic sectional view of an example of a protectivepanel assembly for the medical display shown in FIG. 6A;

FIG. 7 is an explanatory diagram schematically showing a structure of amedical display system according to an embodiment of the presentinvention;

FIG. 8 is a graph showing the relation between the reflectivity andwavelength in anti-reflection films of Example 1 of the presentinvention and Comparative Example 1;

FIG. 9 is a graph showing the color tint of anti-reflection films ofExample 1 of the present invention and Comparative Example 1 on the a*b*plane in CIE 1976 L*a*b* color space; and

FIGS. 10A, 10B, and 10C are explanatory diagrams for illustrating thesurface state of medical displays of Example 2 of the present invention,Comparative Example 2 and Comparative Example 3, respectively, as wellas how incident light is reflected by the medical displays.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A detailed description is given below on a medical display and a medicaldisplay system according to the present invention through preferredembodiments shown in the accompanying drawings.

The description below takes a liquid crystal display device as a typicalmedical display of the present invention, but the present invention isnot limited thereto. A medical display of the present invention can beany matrix display, and the invention is applicable to various imagedisplay devices including plasma display panels (PDPs) andelectroluminescence displays (ELDs, in particular, organic ELDs). Themedical display of the present invention may be a monochrome display, acolor display, or a color display that is capable of displaying amonochrome image.

FIG. 1 shows a schematic side view of a medical display according to anembodiment of the present invention. FIG. 2 is a schematic sectionalview of a liquid crystal display unit of the medical display accordingto the embodiment shown in FIG. 1. FIG. 3 is a schematic sectional viewof a polarization plate in the liquid crystal display unit of FIG. 2 inthe medical display according to the embodiment shown in FIG. 1.

A medical display 10 of FIG. 1 is a matrix display having a resolutionof 100 to 300 ppi (pixel per inch) which receives image data of amedical image taken and processed by a medical measurement (image pickupand diagnostic) apparatus such as an MRI (diagnostic) apparatus, an NMR(diagnostic) apparatus, a CT (diagnostic) scanner, a DSA (diagnostic)apparatus, an FCR (Fuji computed radiography) or other CR (diagnostic)apparatus, a mammography (diagnostic) apparatus, or a digital X-rayradiography (DR) (diagnostic) apparatus and displays the medical imageas a medical diagnostic image. Basically, the medical display 10 has abacklight unit 12, a liquid crystal display unit (hereinafter alsoabbreviated as an LCD unit) 14 and an anti-reflection (hereinafter alsoabbreviated as AR) film 16. In addition, the medical display(hereinafter simply referred to as display) 10 has a display controllingunit (not shown) for controlling display of an image on the LCD unit 14.

The backlight unit 12 serves as a light source of the display 10 touniformly illuminate the entire LCD unit 14 from the back. The backlightunit 12 is a planar light source having approximately the same lightexit plane (light generation plane) as a display screen of the LCD unit14. The light source is composed of a lamp storing unit 12 a and abacklight assembly 12 b. The lamp storing unit 12 a receives a rod-likelamp such as a cold cathode ray tube. The backlight assembly 12 b has anoptical waveguide (not shown) for guiding light emitted from therod-like lamp in a given direction, a reflection sheet (not shown) forreflecting light that has been guided by the optical waveguide in adirection approximately at right angles with the given direction, and adiffusion sheet (not shown) or a prism sheet for uniformizing light thathas been reflected by the reflection sheet.

The backlight unit 12 used in the present invention can be any planarlight source as long as it uses the backlight assembly 12 b that iscomposed of an optical waveguide, a reflection sheet, a diffusion sheet,a prism sheet, etc. to uniformly diffuse light generated by the coldcathode ray tube or the like in the lamp storing unit 12 a. A known LCDbacklight unit is employable as the backlight unit 12. The backlightunit 12 used in the present invention may be an LED array light sourceor a planar light source that uses an organic EL panel or an inorganicEL panel as long as it can emit light of required intensity.

The liquid crystal display unit (LCD unit) 14 is transmissive imagedisplay means for displaying a digitally recorded medical image as adiagnostic image, and receives image data of a diagnostic image takenand processed by the various medical measurement apparatuses asdescribed above and displays the image. The LCD unit 14 may be amonochrome LCD, a color LCD, or a color LCD that is capable ofdisplaying a monochrome image. The display 10 is desirably a displaythat displays a monochrome image from image data of a monochromediagnostic image measured (taken) by a medical measurement apparatusthat uses X-rays, such as a CR apparatus, a mammography apparatus or aDR apparatus, because the present invention can exert its effects bestin that way. More desirably, the display 10 of the present invention isa display that displays a plane (simple) radiographic image or amammographic image taken by a CR apparatus or a flat panel sensor.

FIG. 2 schematically shows a sectional view of the LCD unit 14 accordingto this embodiment.

As shown in FIG. 2, the LCD unit 14 is obtained by layering apolarization plate (a film-like polarization material or a polarizationfilm) 18, a glass substrate 20, an electrode 22, a liquid crystal layer24, an electrode 26, a glass substrate 28, and a polarization plate 30,starting from the side of the backlight unit 12 and proceeding towardthe side of the AR film 16 (see FIG. 1). In short, the LCD unit 14 hasthe liquid crystal layer 24 sandwiched between the glass substrates 20and 28 and the polarization plates 18 and 30 from both sides. The LCDunit 14, as well known, has a black matrix, RGB color filters, anorientation film, and others in addition to those components, althoughnot shown in the drawing. If the LCD unit 14 is a TFT LCD, for example,the electrode 26 is a common electrode, and the black matrix and the RGBcolor filters are placed between the electrode 26 and the glasssubstrate 28 whereas the electrode 22 is composed of a displayelectrode, a gate electrode, and the like. The glass substrates 20 and28 may be replaced by resin substrates or the like.

There is no particular limitation on the LCD unit 14 as long as it has amatrix structure and is capable of displaying a medical image at aresolution of 100 to 300 ppi. If this requirement is met, any LCD thathas a known structure, known structural components and known liquidcrystal display modes, and that is driven by a known driving method canbe employed as the LCD unit 14. Examples of liquid crystal display modesof the LCD unit 14 include the TN mode, the STN mode, the CSH mode, theFLC mode, the OCB mode, and other liquid crystal display modes that usea polarization plate. A matrix driving method is employed to drive theLCD unit 14. Examples of an employable matrix driving method include aTFT active matrix driving method, a diode active matrix driving method,a passive matrix driving method using X-Y stripe electrodes, or thelike.

The resolution of the LCD unit 14, which is an image display unit of thedisplay 10 of the present invention, is limited to 100 to 300 ppibecause, for a 18″ to 23″ screen size, which is suitable to display aplane radiographic image as a diagnostic image, a resolution less than100 ppi is low, and the medical image displayed is pixelized and jagged,making it difficult to interpret minute lineation and calcification,whereas a resolution exceeding 300 ppi is high, and gate materialoptions are limited for a transistor used to matrix-drive the LCD unit14, making the transistor expensive. In addition, when the resolution ishigher than 300 ppi, the aperture ratio is extremely small causing lackof luminance.

The LCD unit 14 of the display 10 of the present invention has to have ahigh definition matrix structure of 100 to 300 ppi (UXGA, QXGA, QSXGA,QUXGA, etc.). When a plane radiographic image taken by a CR apparatus ora flat panel sensor is to be displayed, the LCD unit 14 preferably has aresolution of 100 to 180 ppi. When an image to be displayed is amammographic image which was taken by a CR apparatus or a flat panelsensor and which has minute calcification to be interpreted, theresolution of the LCD unit 14 is preferably 180 ppi to 300 ppi.

In the present invention, the display screen size of the LCD unit 14 ispreferably 18″ to 23″ so that minute calcification and other changes canbe detected with a high definition matrix structure of 100 to 300 ppi.

Given as a preferred example of an LCD monitor that has a resolution of100 to 180 ppi is FC2090, a product of EIZO NANAO CORPORATION (panelsize: 20.8″, number of pixels: QXGA=2048×1536, pixel size: 207 μm=123ppi, a monochrome IPS (In-Plane Switching) display with each pixelhaving sub-pixels). A preferred example of an LCD monitor that has aresolution of 180 to 300 ppi is MD22292, a product of InternationalDisplay Technology Co., Ltd. (panel size: 22.2″, number of pixels:QXGA-W=3840×2400, pixel size: 124.5 μm=204 ppi, a color IPS (In-PlaneSwitching) display with each pixel having RGB sub-pixels).

In the LCD unit 14 structured as above, light projected from thebacklight unit 12 enters the polarization plate 18 and passes throughthe liquid crystal layer 24, where the light is formed into an image(positive image). The light then exits as transmission light from thepolarization plate 30.

The polarization plate 30 constitutes the outermost layer of the LCDunit 14 where the AR film 16 is placed, in other words, the outermostlayer from which transmission light exits. Usually, the polarizationplate 30 is covered with a protective film, which is matted (roughened)on the front side or the rear side, preferably on the rear side, toobtain an anti-glare property. The polarization plate 30 in the presentinvention is preferably covered with a protective film having smoothfront and rear surfaces that are not matted and that have no anti-glareproperty.

FIG. 3 is a schematic sectional view showing the structure of thepolarization plate 30 adhered to the glass substrate 28 of the LCD unit14 and the structure of the AR film 16 adhered to the polarization plate30 in this embodiment.

As shown in FIG. 3, the polarization plate 30 is adhered to the glasssubstrate 28 through an adhesion layer 32. The polarization plate 30has, starting from the side of the glass substrate 28 (the adhesionlayer 32) and proceeding toward the side of the AR film 16, a supportlayer 34, a polarization film 36, a support layer 38, and a hard coatlayer (hereinafter abbreviated as HC layer) 40. The support layers 34and 38 are each made of a TAC film or the like. The polarization film 36is a PVA/I film or the like having a polarization function (the PVA/Ifilm is obtained by staining a polyvinyl alcohol (PVA) film with iodine(I) and stretching the film). The HC layer 40 is the topmost layer andserves as a protective film.

In addition to the above, the polarization plate 30 of the presentinvention can employ known materials for the support layers 34 and 38and for the polarization film 36.

Any material can be used for the HC layer 40 of the present invention aslong as it functions as a protective film of the LCD. However, whenemployed as the LCD unit 14 is a known IPS LCD, the HC layer 40 has tohave electrical conductivity.

It is preferable that the HC layer 40 of the present invention is notmatted on both the front and rear surfaces but flat and smooth, has noanti-glare property, and works to make transmission light from the LCDunit 14 exit with less scattering. In order to reduce scattering of thetransmission light to the lowest possible level, the side of the HClayer 40 from which the transmission light exits the polarization plate30 has to have a flat and smooth surface. Specifically, the arithmeticaverage height (Ra, JIS B 0601-2001) of the smooth surface is set at0.02 μm or less. The arithmetic average height is desirably set at 0.01μm or less. The maximum height (Rz, JIS B 0601-2001) of the smoothsurface is set at 0.04 μm or less, more desirably, 0.02 μm or less. Thesupport layer 38 on which the HC layer 40 is formed preferably has aflat and smooth surface. The arithmetic average height (Ra, JIS B0601-2001) of the surface of the support layer 38 is set at 0.02 μm orless. The arithmetic average height is desirably set at 0.01 μm or less.The maximum height (Rz, JIS B 0601-2001) of the smooth surface of thesupport layer 38 is set at 0.04 μm or less, more desirably, 0.02 μm orless.

The AR film 16, which characterizes the present invention most, isplaced on the LCD unit 14.

The AR film 16 has an average specular reflectivity of 0.5% or less atan incident angle of 5° in a wavelength range of 450 to 650 nm. Thismakes it possible to sufficiently prevent external light reflected onthe surface of the display 10 from lowering the visibility.

The AR film 16 receives light from a CIE standard light source D65 at anincident angle of 5° in a wavelength range of 380 to 780 nm and reflectsthe light as regular reflection light whose color tint falls within arange of −7≦a*≦7 and −10≦b*≦10 in terms of a* and b* values of CIE 1976L*a*b* color space. This reduces the reddish purple to bluish purplecolor in reflected light, which has been a problem of conventionalmultilayer anti-reflection films. The great reduction in color tint ofreflected light leads to a great reduction in uneven color tint ofreflected light which is caused by uneven thickness of ananti-reflection layer (AR layer 48, see FIG. 3). More desirably, theaverage specular reflectivity is 0.3% or less, and a* and b* satisfy0≦a*≦5 and −7≦b*≦0. In this way, the visibility and color tint ofreflected light are reduced even more, and when applied to a liquidcrystal display device (for example, the LCD unit 14), the AR film 16can neutralize, to an unnoticeable degree, color tint on the displayscreen reflecting a small amount of external light that has as highluminance as in an indoor fluorescent light.

The AR film 16 has no anti-glare property. Therefore, when used in amedical display that has a high definition matrix structure of 100 to300 ppi, especially a medical display used for interpretation of amammographic image which contains minute calcification etc., a displayedimage is not blurred but has vividness and sharpness while seriousglaring is avoided. In addition, the displayed image is not shifted inthe front-to-back direction and therefore has no ‘double vision’ look.Furthermore, the screen does not assume a whitish appearance, thuspreventing dark areas from looking protruded and avoiding lowering ofcontrast. A diagnosis can therefore be made without trouble.

The AR film 16 having such characteristics is adhered to the HC layer40, which is the outermost layer of the LCD unit 14, through an adhesionlayer 42 as shown in FIG. 3, and has a transparent support layer 44, ahard coat layer (hereinafter also abbreviated as HC layer) 46, and theAR layer. 48 starting from the side of the HC layer 40 (the adhesionlayer 42) and proceeding outward. The transparent support layer 44 ismade of a TAC film or the like.

As shown in FIG. 4, the AR layer 48 has practically three sub-layers: anintermediate refractive sub-layer 50, a high refractive sub-layer 52,and a low refractive sub-layer 54, with these sub-layers 50, 52 and 54being arranged in this order outwardly from the HC layer 46 side.

In order to achieve the reflectance characteristics which lower thereflectivity and which reduce color tint, refractive indexes n1, n2, andn3 of the intermediate refractive sub-layer 50, the high refractivesub-layer 52 and the low refractive sub-layer 54, which are respectivelythe three sub-layers of the AR layer 48 placed on the HC layer 46 in theAR film 16, preferably satisfy the following relations when therefractive index of the transparent support layer 44 is given as n_(B),and the refractive index of the HC layer 46 that is placed on thetransparent support layer 44 is given as n_(H).n3<n_(B), n_(H)<n1<n2

It is preferable for the intermediate refractive sub-layer 50, the highrefractive sub-layer 52 and the low refractive sub-layer 54, that is,the sub-layers of the AR layer 48, to satisfy at a design wavelength λ(500 nm) the following expressions (I), (II) and (III), respectively:λ/4×0.80<n1×d1<λ/4×1.00  (I)λ/2×0.75<n2×d2<λ/2×0.95  (II)λ/4×0.95<n3×d3<λ/4×1.05  (III)where d1 represents the thickness (nm) of the intermediate refractivesub-layer 50, d2 represents the thickness (nm) of the high refractivesub-layer 52, and d3 represents the thickness (nm) of the low refractivesub-layer 54.

For instance, when the transparent support layer 44 is formed oftriacetyl cellulose (refractive index: 1.49), the refractive index n1 ispreferably 1.60 to 1.65; n2, 1.85 to 1.95; and n3, 1.35 to 1.45. Whenthe transparent support layer 44 is formed of polyethylene terephthalate(refractive index: 1.66), the refractive index n1 is preferably 1.65 to1.75; n2, 1.85 to 2.05; and n3, 1.35 to 1.45.

If it is not possible for some reason to choose materials that can givethe intermediate refractive sub-layer 50 and the high refractivesub-layer 52 refractive indexes in those ranges, a layer that ispractically optically equivalent to the intermediate refractivesub-layer 50 or the high refractive sub-layer 52 that has the setrefractive index can be formed by utilizing the principle of equivalentfilm in which a layer having a higher refractive index than a setrefractive index is combined with a layer having a lower refractiveindex than the set refractive index. This well-known solution is alsoapplicable to obtain the above-described reflectance characteristics ofthe AR film 16. In the present invention, the phrase “has practicallythree sub-layers” means that the AR layer 48 may also be composed offour, five, or more sub-layers if an equivalent film as such is used.

The transparent support layer 44 is preferably a plastic film. Examplesof plastic film materials include triacetyl cellulose (TAC) and othercellulose esters, polyamide, polycarbonate, polyester, polystyrene,polyolefin, polysulfone, polyether sulfone, polyarylate, polyetherimide, polymethyl methacrylate, polyether ketone, and the like.

The light transmittance of the transparent support layer 44 is desirably80% or higher, more desirably, 86% or higher. The haze ratio of thetransparent support layer 44 is desirably 2.0% or lower, more desirably,1.0% or lower. The refractive index of the transparent support layer 44is preferably 1.4 to 1.7.

A triacetyl cellulose (TAC, refractive index: 1.49) film is preferred asthe transparent support layer 44 particularly when the AR film 16 isadhered to a polarization plate (for example, the polarization plate 30of the LCD unit 14) or constitutes one side of a surface protective filmin order to obtain a liquid crystal display device (the LCD unit 14), anorganic EL display device, or the like. A known triacetyl cellulose filmsuch as TAC-TD 80U (a product of Fuji Photo Film Co., Ltd.) makes asatisfactory transparent support layer 44. The material of thetransparent support layer 44 can be used also in the support layers 34and 38 of the polarization plate 30 of the LCD unit 14.

On the other hand, when the AR film 16 is adhered to a glass substrateor the like in order to obtain a flat CRT, a PDP, or the like, thetransparent support layer 44 is preferably formed of polyethyleneterephthalate (PET, refractive index: 1.66) or polyethylene naphthalate.

The HC (hard coat) layer 46 is provided to give the transparent supportlayer 44 an anti-abrasion property. The HC layer 46 also has a functionof enhancing adhesion between the transparent support layer 44 and alayer formed thereon. A preferable method to form the HC layer 46 isstarted with application of an application composition that is obtainedby adding an inorganic filler to a composition, which is prepared bydissolving in a solvent, oligomers such as multifunctional acrylicmonomers, urethane acrylates, epoxy acrylates, and variouspolymerization initiators. The inorganic filler is silica, alumina, orthe like and is added in accordance with reinforcement and other needs.Then, the solvent is dried and the applied composition is cured by heatand/or ionizing radiation. The same method can be used to form the HClayer 40 of the polarization plate 30 of the LCD unit 14.

Of the three sub-layers of the AR layer 48, the intermediate refractivesub-layer 50 and the high refractive sub-layer 52 are formed by applyingan application composition, which contains inorganic fine particles highin refractive index, a monomer curable by heat or ionizing radiation, apolymerization initiator, and a solvent, drying the solvent, and thencuring the applied composition by heat and/or ionizing radiation. Theinorganic fine particles are preferably particles of at least one kindof metal oxide chosen from oxides of Ti, Zr, In, Zn, Sn, and Sb. Thethus formed intermediate refractive sub-layer 50 and high refractivesub-layer 52 are superior in anti-abrasion property and adhesion to onesthat are obtained by applying and then drying a polymer solution withhigh refractive index. In order to ensure the dispersion liquidstability, the strength of the cured film, and the like, the applicationcomposition desirably contains a multifunctional (meth)acrylate monomerand an anionic group-containing (meth)acrylate dispersion liquid.

The inorganic fine particles preferably have a mean particle size of 1to 100 nm when measured by the Coulter counter method. If the meanparticle size is less than 1 nm, the specific surface area is too large,and the fine particles lack stability in the dispersion liquid, which isundesirable. On the other hand, inorganic fine particles whose meanparticle size exceeds 100 nm cause scattering of visible light due to adifference in refractive index between the particles and the binder,thus undesirably increasing the haze ratio. The haze ratio of theintermediate refractive sub-layer 50 and the high refractive sub-layer52 is desirably 3% or less, more desirably, 0.5% or less.

A fluorine-containing resin curable by heat or ionizing radiation isused in the low refractive sub-layer 54. Examples of this curable,fluorine-containing resin include a perfluoroalkyl group-containingsilane compound (e.g., (heptadecafluoro-1,1,2,2-tetradecyl)triethoxysilane), and a fluorine-containing copolymer that has as itsstructural units a fluorine-containing monomer and a monomer thatprovides the cross-linking ability.

Specific examples of a fluorine-containing monomer unit includefluoroolefins such as hexafluoropropylene, partially or fullyfluorinated alkyl ester derivatives of (meth)acrylic acid, and partiallyor fully fluorinated vinyl ethers. Of these examples,hexafluoropropylene is particularly desirable in view of low refractiveindex and ease of handling the monomer.

Employed as a monomer that provides the cross-linking ability is, forexample, glycidyl methacrylate or other (meth)acrylate monomerpossessing a cross-linkable functional group in its molecule, or a(meth)acrylate monomer having a carboxyl group, a hydroxyl group, anamino group, a sulfonic acid group, or the like.

In place of a polymer that has the above fluorine-containing monomer asits structural unit, a copolymer including a fluorine-free monomer maybe employed.

Preferably, a fluorine-containing resin used to form the low refractivesub-layer 54 is given an anti-abrasion property by adding ultra-fineparticles of a silicon oxide. The anti-abrasion property deteriorates asthe refractive index of the fluorine-containing resin is lowered,although a lower refractive index means better anti-reflection property.Accordingly, the refractive index of the fluorine-containing resin andthe amount of silicon oxide ultra-fine particles added are optimized toreach the best balance between anti-abrasion property and low refractiveindex.

As to silicon oxide ultra-fine particles, a commercially-availablesilica sol in which silica is already dispersed in an organic solventmay be added as it is to the application composition. Alternatively, thesilicon oxide ultra-fine particles may be prepared by dispersing varioustypes of commercially-available silica powder in an organic solvent.

The AR film 16 may additionally have a forward scattering layer, ananti-static layer, an undercoat layer, and a protective layer.

The forward scattering layer provides an effect of improving the viewingangle when the AR film 16 is applied to a liquid crystal display device,and the viewing angle is tilted vertically and laterally. If fineparticles having different refractive indexes are diffused in the HClayer 46, a hard coat function is obtained at the same time.

Each layer of the AR film 16 can be formed by application. Examples ofapplication methods employable for the layers of the AR film 16 includedip coating, air knife coating, curtain coating, roller coating, wirebar coating, gravure coating, micro-gravure coating, and extrusioncoating. Of these application methods, micro-gravure coating and gravurecoating are desirable since the two methods require a minimum wetapplication amount and thus the coat dries evenly. The gravure method inparticular is preferred from the viewpoint of obtaining uniform filmthickness in the lateral direction. Two or more layers may be applied atthe same time.

In the present invention, the anti-glare property for obscuringreflection of background light on the display screen must not beimparted when forming the multilayer AR film 16 by wet application ofthe application composition. Specifically, the front surface of the ARfilm 16, in particular, the front surface (and preferably rear surface)of the HC layer 46 and the AR layer 48 have to be flat and smooth unlikein the common treatment in which the AR layer 48 is formed on the frontsurface of the HC layer 46 that is made uneven by including matteparticles or the like, or the front surface of the AR layer 48 is madeirregular by embossing or other method.

In a preferred embodiment of the present invention, both sides of the ARfilm 16, in particular, the front and rear surfaces of the HC layer 46and the AR layer 48 are not matted, but the AR film 16 is flat andsmooth and has no anti-glare property. The AR film 16 should work tolessen scattering when transmission light from the LCD unit 14 exits theAR film 16. In order to reduce scattering of transmission light to thelowest possible level, the side of the AR layer 48 of the AR film 16from which transmission light exits has to have a flat and smoothsurface. Specifically, the arithmetic average height (Ra, JIS B0601-2001) of the smooth surface is set at 0.02 μm or less. Moredesirably, the arithmetic average height is set at 0.01 μm or less. Themaximum height (Rz, JIS B 0601-2001) of the smooth surface is set at0.04 μm or less, more desirably, 0.02 μm or less.

By making the surface flat, the AR film 16 can have more uniformthickness, which brings out desirable results in reduction of unevencolor tint and improvement in AR performance.

The transparent support layer 44 on which the HC layer 46 is formedpreferably has a flat and smooth surface. The arithmetic average height(Ra, JIS B 0601-2001) of the surface of the support layer 44 is set at0.02 μm or less. The arithmetic average height is desirably set at 0.01μm or less. The maximum height (Rz, JIS B 0601-2001) of the smoothsurface is set at 0.04 μm or less, more desirably, 0.02 μm or less.

The embodiment shown in FIG. 3 is also applicable for a medical displaythat utilizes a conventional liquid crystal display device or when acommercially-available liquid crystal display device is used as amedical display as long as the display has a resolution of 100 to 300ppi. The AR film 16 in this embodiment is adhered with an adhesive tothe outer surface of the polarization plate 30, which constitutes theoutermost layer of the LCD unit 14. However, the present invention isnot limited thereto, and a variation shown in FIG. 5 may be employed. InFIG. 5, the support layer 38 and the HC layer 40 of the polarizationplate 30 double as the support layer 44 and the HC layer 46 of the ARfilm 16 to create a new polarization plate 56 with the AR layer 48 inwhich the polarization plate 30 and the AR film 16 are integrallyformed. The polarization plate 56 is adhered to the glass substrate 28of the LCD unit 14 through the adhesion layer 32.

In other words, instead of bonding the AR film 16 through the adhesionlayer 32 to the completed LCD unit (LCD panel) 14 to which thepolarization plate 30 has already been attached, the polarization plate56 in which the AR film 16 constitutes one side of a surface protectivefilm of a polarizer (the polarization film 36) may be employed. In thisway, the AR property can be obtained in the process of manufacturing theLCD panel 14.

The polarization plate 56 shown in FIG. 5 is adhered to the glasssubstrate 28 through the adhesion layer 32. The polarization plate 56has, starting from the side of the glass substrate 28 (the adhesionlayer 32) and proceeding outward, the support layer 34, the polarizationfilm 36, the support layer 38, the HC layer 40, and the AR layer 48,which is the topmost layer. Accordingly, it can be said that thepolarization plate 56 is obtained by forming, through application, forexample, the AR layer 48 on the polarization plate 30 of FIG. 3 which iscomposed of the support layer 34, the polarization film 36, the supportlayer 38, and the HC layer 40. It can also be said that the polarizationplate 56 is obtained by replacing the surface protective film which iscomposed of the support layer 38 and the HC layer 40 on one side of thepolarization plate 30 of FIG. 3 with the AR film 16.

The embodiment shown in FIG. 5 needs to incorporate the dedicatedpolarization plate 56 in a medical display of the present invention. Onthe other hand, the embodiment shown in FIG. 5 requires less interveninglayers than the embodiment shown in FIG. 3 does and therefore canprovide a wider dynamic range of shades for a displayed image, thusmaking the image appropriate as a diagnostic image.

In the embodiments described above, the AR layer 48 or the AR film 16 isplaced on the front surface of the display 10, or the polarization plate56 with the AR layer 48 constituting the topmost layer is employed asthe polarization plate of the LCD unit 14 or is adhered to the frontsurface of the LCD unit 14. However, the present invention is notlimited to the above embodiments, and a protective panel assembly 62shown in FIGS. 6A and 6B may be employed. The protective panel assembly62 is obtained, as shown in FIG. 6B, by bonding the AR film 16 throughan adhesive layer to each side (the front and rear surfaces) of aprotective panel 64, which is a transparent acrylic board or the like.As shown in FIG. 6A, the protective panel assembly 62 is attached to thefront of a medical display 60 while securing a given distance betweenthe assembly 62 and the display screen of the display 60, that is, thefront surface of the LCD unit 14, and thus avoiding a contact betweenthe two.

Although the AR film 16 is bonded to each side of the protective panel64 with an adhesive in the medical display 60 of FIGS. 6A and 6B, thepresent invention is not limited thereto. Instead, the AR layer 48 maybe formed by, for example, application on each side of the transparentprotective film 64 to obtain the protective panel assembly 62.

When the gradation of the medical display 10 or 60 is corrected(calibrated) according to GSDF of DICOM in a medical display system,which will be described later, a gradation correction table is madetaking into account the medical display's surface reflection luminance(hereinafter also referred to as peripheral light reflection luminance)which is dependent on environmental light or external light in additionto the luminance of the medical display. Measuring the peripheral lightreflection luminance with accuracy requires a remote-sensing luminancemeter. However, the remote-sensing luminance meter is not easy tohandle, and a contact type luminance meter is often employed for thesake of convenience. It is preferable to use the remote-sensingluminance meter in periodical measurement of the peripheral lightreflection luminance by a service person or a maintenance person while,on a day-to-day basis, the contact type luminance meter is used tomeasure the peripheral light reflection luminance and correction is madeon the measurements before the data are used (see commonly assignedJapanese Patent Application No. 2003-0264843).

In this case, if the contact type luminance meter is brought into directcontact with the front surface of the LCD unit (panel) 14, the LCD unit(panel) 14 is deformed by the pressure and the display luminance isfluctuated as a result. For that reason, it is desirable to place theprotective panel 64 or the protective panel assembly 62 at a givendistance from the front surface of the LCD unit (panel) 14 as shown inFIG. 6A. When placing the protective panel 64, the AR property has to beprovided by adhering the AR film 16 to the protective panel 64 or byforming the AR layer 48 on the protective panel 64.

Therefore, the distance between the front surface of the LCD unit 14 andthe protective panel 64 or the protective panel assembly 62 should belarge enough to avoid deformation of the LCD unit (panel) 14 andfluctuation in display luminance when the contact type luminance meteris brought into direct contact with the protective panel 64 or theprotective panel assembly 62. On the other hand, too large a distancebetween the LCD unit 14 and the protective panel 64 or the protectivepanel assembly 62 is not desirable for observation. An appropriate gapis chosen from between 2 mm and 20 mm, for example, to suit the rigidityof the protective panel 64. Usually, about 5 to 20 mm is appropriate,but the gap may be set at 2 to 10 mm if the protective panel 64 has highrigidity.

When adhered to the polarization plate 30 of the LCD unit (panel) 14 asshown in FIG. 3, or when constituting one side of the surface protectivefilm of the polarizer as shown in FIG. 5, the AR film 16 of the presentinvention is suitable for transmissive, reflective, or semi-transmissiveliquid crystal display devices (LCDs) which are of twisted nematic (TN)mode, super twisted nematic (STN) mode, vertical alignment (VA) mode,in-plane switching (IPS) mode, optically-compensated bend cell (OCB)mode, or the like and which are applicable as medical displays. If theAR film 16 of the present invention is used in combination with acommercially-available luminance improving film (a polarization splitterfilm having a polarization selective layer, for example, D-BEF, aproduct of Sumitomo 3M) in a transmissive or semi-transmissive liquidcrystal display device, the display device can have even highervisibility.

When placing a protective panel (front panel) such as an acrylic boardover the entire surface of a liquid crystal cell of a transmissive,reflective, or semi-reflective liquid crystal display device with airfilling a gap between the liquid crystal cell and the protective panelas shown in FIGS. 6A and 6B, it is preferable to apply, through anadhesive or the like, the AR film 16 to the inside and/or outside of theprotective panel (front panel) as well as to a polarization plate on thefront side of the liquid crystal cell since reflection at the interfaceis reduced. If combined with a λ/4 plate, the AR film 16 can be used asa surface protective plate for reflective or semi-transmissive LCDs andorganic EL displays. Furthermore, by forming the AR layer on atransparent support made of PET, PEN, or the like, the present inventionis applicable to image display devices such as plasma display panels(PDPs) and cathode ray tube display devices (CRTs).

Basically, a medical display of the present invention is structured asabove.

In a particularly desirable mode of a medical display according to thepresent invention, a gradation correction table is made taking intoaccount the peripheral light reflection luminance (surface reflectionluminance dependent on environmental light when the power is turned off)in addition to the luminance of the medical display to correct(calibrate) the gradation of the medical display in accordance with GSDFof DICOM for the quality control (QC) of the medical display. Therefore,the peripheral light reflection luminance has to be measured accuratelyas well as the luminance of the medical display.

For that reason, a medical display of the present invention is mosteffective when built into a medical display system equipped with aluminance meter that is capable of measuring the peripheral lightreflection luminance as well as the luminance of the medical displaywith accuracy. An embodiment of such medical display system is shown inFIG. 7.

A medical display system (hereinafter simply referred to as system) 70shown in FIG. 7 has the display 10 described above and a luminance meter72. The display 10 has the LCD unit 14, the AR film 16, a backlight unit(not shown in FIG. 7, see the backlight unit 12 in FIG. 1), and adisplay controlling unit 74.

In the embodiment shown in FIG. 7, the system 70 has the display 10 as atypical example. However, the present invention is not limited to thedisplay 10 and any image display device that is applicable to a medicaldisplay of the present invention can be employed in the system. Imagedisplay devices of the various modes given in the above as well as thedisplay 60 shown in FIGS. 6A and 6B are employable by the system.

The luminance meter 72 measures, in addition to the display luminance ofthe medical display 10, the peripheral light reflection luminance withaccuracy, in other words, the display luminance (luminance of eachportion when a test pattern is displayed) of the display screen when thepower of the LCD unit 14 of the display 10 is turned on (while thebacklight unit is lit), namely, in the present invention (the system70), the display luminance through the AR film 16, in particular, themaximum luminance, the minimum luminance, and the surface reflectionluminance of the display screen when the power of the LCD unit 14 isturned off (while the backlight unit is turned off and no image isdisplayed) (which will be also hereinafter referred to as peripherallight reflection luminance), namely, in the present invention, thesurface reflection luminance of the AR film 16.

The luminance meter 72 can be one chosen from known luminance meters inaccordance with the types of medical displays applicable to the presentinvention. However, a remote-sensing luminance meter is preferred inorder to measure with accuracy the display's luminance as well as theperipheral light reflection luminance. As described above, aremote-sensing luminance meter should be chosen particularly in thedisplay 10 or other liquid crystal display devices (LCDs) and organic orother ELDs and PDPs where a contact between the display screen and acontact type luminance meter affects displayed image.

On the other hand, when attaching a luminance meter to the displayscreen does not affect a displayed image as in CRTs, a contact typeluminance meter which is simpler and easier to handle can be employedsince a remote-sensing luminance meter is not easy to handle. If it isdesired to use a contact type luminance meter in a medical displaysystem that has an LCD, an ELD, or a PDP, a protective panel assembly isemployed as in FIGS. 6A and 6B where the protective panel assembly 62 isattached to the casing of the display 60, or a protective panel such asthe protective panel 62, which is attached to the casing of the display10 shown in FIG. 1, is employed.

In the case where the simpler option is chosen and a contact typeluminance meter is used to measure the display's luminance, themeasurements may be immediately put into use but it is preferable tomeasure the peripheral light reflection luminance with a remote-sensingluminance meter in maintenance works or periodic calibration by aservice person or a maintenance person while the contact type luminancemeter is used for routine calibration and, before the measurements areput into use, correction is made on the data in light of the peripherallight reflection luminance measured by the remote-sensing luminancemeter.

According to this method of measuring the display's luminance, accurateluminance measurements can always be obtained and measurement deviationcaused by brightness of external light (peripheral light) depending onwhere the display is set up can be corrected appropriately (for details,see commonly assigned Japanese Patent Application No. 2003-0264843).

In the present invention, it is preferable to connect the luminancemeter 72 and the display 10 (the display controlling unit 74) online asin the embodiment shown in FIG. 7, so that the luminance can be measuredin sync with display of a luminance measurement test pattern on thedisplay screen of the display 10. This synchronization is achieved by aluminance meter controlling section 76 of the display controlling unit74 which will be described later.

Although the luminance meter 72 is connected online to the display 10(the display controlling unit 74) in the embodiment shown in FIG. 7, thepresent invention is not limited thereto. For instance, a luminancemeter that is not connected online to the display 10 may be used tomeasure the luminance of the display 10 which is then inputted to thedisplay controlling unit 74 of the display 10 using a keyboard or thelike.

The display controlling unit 74 is a unit for controlling all there isto display an image on the LCD unit 14, including calibration of animage displayed on the LCD unit 14. The display controlling unit 74 hasthe luminance meter controlling section 76, a measurement data judgingsection (hereinafter simply referred to as judging section) 78, ameasurement data and judgment result memory (hereinafter abbreviated asmemory) 80, a gradation correcting section 82, a test pattern generatingsection 84, a data processing section 86, and a driver 88.

The luminance meter controlling section 76 has a function of controllingthe luminance meter 72, the backlight unit of the display 10, the testpattern generating section 84, and the driver 88 to measure the surfacereflection luminance (peripheral light reflection luminance) of thedisplay 10 when the power is turned off and the display luminance of thedisplay 10 when the power is turned on (hereinafter abbreviated asdisplay luminance). The luminance meter controlling section 76 of theembodiment shown in FIG. 7 turns off the backlight unit in the LCD unit14 of the display 10 and controls the luminance meter 72 to measure asthe peripheral light reflection luminance the surface reflectionluminance of the AR film 16 on the LCD unit 14. On the other hand, theluminance meter controlling section 76 turns the backlight unit on,controls the driver 88 to drive the LCD unit 14 to display a luminancemeasurement test pattern (test chart) based on test pattern data thatwas generated by the test pattern generating section 84, and controlsthe luminance meter 72 to measure the display luminance of the luminancemeasurement test pattern displayed on the LCD unit 14 (the luminance ofeach portion of the pattern, namely, each test chart). When theluminance meter 72 is connected online to the display 10 (the displaycontrolling unit 74) as in the embodiment shown in FIG. 7, the luminancemeter controlling section 76 preferably commands the luminance meter 72to start measuring the luminance in sync with display of the luminancemeasurement test pattern on the display screen of the display 10.

For the QC of the display, the judging section 78 judges measurementdata including the surface reflection luminance measured by theluminance meter 72 when the power is turned off and the displayluminance (maximum luminance, minimum luminance, and the like) measuredby the luminance meter 72 when the power is turned on.

For instance, if an invariance test is an item of the QC, the judgingsection 78 calculates the rate or amount of change of measurement datafrom the initial value, namely, the initial surface reflection luminanceor the initial display luminance (maximum luminance, minimum luminance,and the like), and judges whether or not the obtained rate of change oramount of change is within a preset acceptable range.

The judging section 78 may also be structured to judge that gradationcorrection is necessary when the judgment result of measurement data isoutside the acceptable range in the invariance test or, even if withinthe acceptable range, meets a preset condition. An example of the lattercase is when the amount or rate of change in maximum luminance does notbalance with the amount or rate of change in minimum luminance.

The measurement data including the peripheral light reflection luminanceand the display luminance (maximum luminance and minimum luminance)measured by the luminance meter 72, and the result of judgment made bythe judging section 78 based on the measurement data are sent as displaydata from the judging section 78 to the data processing section 86. Thedata processing section 86 converts the display data into drive signalsand sends the signals to the driver 88. The display data are thendisplayed on the LCD unit 14 by the driver 88. Accordingly, the judgingsection 78 of the display controlling unit 74 also has a function ofdisplaying the measurement data and judgment result on the display. Themeasurement data and judgment result may be outputted in the form of ahard copy by a printer (not shown) or the like in place of displaying onthe display.

The measurement data and judgment result are displayed on the LCD unit14 of the display 10, which is for displaying a medical image, in theembodiment shown in FIG. 7. However, the present invention is notlimited thereto and the data may be displayed on other displays, forexample, other medical displays, administrative displays, and monitors(displays) of personal computers or the like for administrative use.

The memory 80 has a function of storing measurement data including theperipheral light reflection luminance and the display luminance (maximumluminance and minimum luminance) measured by the luminance meter 72 (inshort, luminance measurement results), a result of judgment made by thejudging section 78 based on the measurement data (in short, qualitycontrol result), a gradation characteristic result, and the history ofthese results. The luminance measurement results, quality controlresult, gradation characteristic result, and history of these resultswhich are stored in the memory 80 can be read out to be displayed oroutputted in the form of a hard copy as the need arises.

The gradation correcting section 82 displays a medical diagnostic imageon the LCD unit 14 at an appropriate luminance and in a given gradation.The gradation correcting section 82 makes or calibrates a gradationcorrection table (LUT) for correcting the gradation of medicaldiagnostic image data to obtain image data that has a given luminanceand gradation (gradation characteristic), preferably, gradation datahaving a luminance that conforms to GSDF of DICOM. The gradationcorrecting section 82 also stores the gradation correction table and,using the stored gradation correction table, converts image data of amedical diagnostic image supplied from an external medical measurementapparatus (image pickup and diagnostic) apparatus or the like into imagedata having a given gradation characteristic (GSDF of DICOM).

For example, when correcting the gradation in accordance with GSDF ofDICOM, the gradation correcting section 82 determines, as a gradationcharacteristic (hereinafter referred to as measured gradationcharacteristic), the peripheral light surface reflection luminance ofthe display 10 and the relation between the size of input image datanecessary to display each portion (e.g., gray scale) of a display testpattern, and the size of measurement data of the display luminance ineach portion (gray scale) of the test pattern displayed on the display10. The gradation correcting section 82 compares the measured gradationcharacteristic obtained with the gradation characteristic of GSDF ofDICOM, and creates a gradation correction table such that the gradationcharacteristic of each portion (gray scale) of the test pattern matchesthe gradation characteristic of GSDF. When making the gradationcorrection table in the gradation correcting section 82, acharacteristic value at a point between two portions (gray scales) ofthe test pattern can be obtained by interpolation, for example, linearinterpolation or secondary interpolation.

Next, the gradation correcting section 82 uses the thus createdgradation correction table to correct the gradation of the test patterndata generated by the test pattern generating section 84. The obtainedtest pattern data with corrected gradation is converted in the dataprocessing section 86 into drive signals for the LCD unit 14 to displaythe test pattern on the LCD unit 14 of the display 10. Thereafter, thedisplay luminance of the test pattern displayed on the display 10 ismeasured again to obtain a measured gradation characteristic of thedisplay 10, and the measured gradation characteristic obtained iscompared with the gradation characteristic of GSDF.

At this point, if the error between the measured gradationcharacteristic and the gradation characteristic of GSDF is within agiven range, calibration of the gradation correction table is ended.

On the other hand, if the error between the measured gradationcharacteristic and the gradation characteristic of GSDF is outside thegiven range, calibration of the gradation correction table is repeatedin the manner described above until the error between the measuredgradation characteristic and the gradation characteristic of GSDF fallswithin the given range.

In this way, the gradation correcting section 82 creates or calibrates agradation correction table for achieving appropriate gradationcorrection (for details about the QC of the display which includes aninvariance test and calibration, see commonly assigned Japanese PatentApplication No. 2002-332335). Through such quality control of a medicaldisplay, stable observation of a displayed image which is an optimalrepresentation of image data is always ensured in any kind of medicaldisplay system.

DICOM regulates that a test pattern displaying each portion (gray patch)against a background whose luminance is 20% of the maximum luminance ofthe display device in question must be used to correct the displaygradation of the display device in accordance with the gradationcharacteristic of GSDF. Therefore, a preferable way is to display a testpattern on the display device, then measure the displayed test patternin pre-measurement to obtain the 20% luminance level of the maximumluminance of the display device, make a modification to display the testpattern against a background that has the 20% luminance level, and thenmeasure the luminance for creating or calibrating a gradation correctiontable. In this way, automatic luminance measurement and calibration aremade possible (for details, see commonly assigned Japanese PatentApplication No. 2002-374588). A test pattern or the like regulated withdisplay luminance can thus be displayed in measuring the luminance of amedical display. For instance, when creating a gradation correctiontable according to the GSDF gradation of DICOM, the gradation correctiontable can be made from the luminance measured accurately and thereforethe objective gradation characteristic is attained and appropriate imagedisplay is achieved.

The test pattern generating section 84 is for generating test patterndata in order to display on the display 10 a test pattern necessary forthe QC of the display 10. Test patterns generated by the test patterngenerating section 84 are not limited to ones for the invariance testand the calibration described above. Examples of test patterns that canbe generated by the test pattern generating section 84 include a grayscale pattern for evaluating the reproducibility of gray scale which isregulated by JIS Z4752-2-5, a resolution pattern for evaluating thereproducibility of the resolution, a screen distortion pattern forevaluating the distortion of an image, a color pattern for evaluatingthe reproducibility of colors, and an SMPTE pattern for visual checkwhich is regulated by SMPTE RP (Recommended Practice)-133.

The data processing section 86 converts test pattern data generated bythe test pattern generator 84, image data of a medical diagnostic imagesupplied from a medical measurement (image pickup and diagnostic)apparatus or the like, measurement data from the luminance meter 72, anda result of judgment made by the judging section 78 into drive signals,which are sent to the driver 88. The driver 88 drives the LCD unit 14 todisplay the data.

The driver 88 is for modulation driving the LCD unit 14 to display onthe LCD unit 14 a test pattern, a medical diagnostic image, luminancemeasurement data, and a judgment result in response to drive signalssupplied from the data processing section 86.

Basically, a medical display system of the present invention isstructured as above.

A specific description is given below on the present invention throughExamples.

EXAMPLE 1

An AR film 16 for use in the medical display 10 of the present inventionwas made in the manner described below. Each AR film sample was preparedby application using a gravure coater.

In a first step, an application solution containing silica filler andUV-curable acrylic resin was applied to the top face of the transparentsupport layer (refractive index: 1.49, thickness 80 μm) 44, which wasmade from a triacetyl cellulose film, TAC-TD 80U (a product of FujiPhoto Film Co., Ltd.). The applied solution was dried and cured byultra-violet irradiation to form a hard coat layer (refractive index:1.51, thickness 6 μm) 46.

In a second step, an application solution containing dispersed titaniumdioxide having a mean particle size as measured by the Coulter method of42 nm, and UV-curable acrylic resin was applied to the top face of thehard coat layer 46. The applied solution was dried and cured byultra-violet irradiation to form an intermediate refractive sub-layer(refractive index: 1.63, thickness 67 μm) 50.

In a third step, an application solution which was similar to the oneused in the second step but was increased in weight ratio of titaniumdioxide was applied to the top face of the intermediate refractivesub-layer 50. The applied solution was dried and cured by ultra-violetirradiation to form a high refractive sub-layer (refractive index: 1.90,thickness 107 μm) 52.

In a fourth and last step, an application solution containingthermally-curable fluorine polymer and silica sol was applied to the topface of the high refractive sub-layer 52. The applied solution was driedand cured by heat to form a low refractive sub-layer (refractive index:1.43, thickness 86 nm) 54.

The AR film 16 used in the medical display 10 of the present inventionwas thus obtained. When measured by an AFM (Atomic Force Microscope),the AR film had such surface roughness that Ra=0.005 μm or less andRz=0.01 μm or less.

The refractive indexes n and thicknesses d of the refractive layers ofthe AR film 16 according to Example 1 were checked against the designformula with the design wavelength λ set at 500 nm.

1) The value nd (n1×d1) of the intermediate refractive sub-layer 50 is109.21 and satisfies Expression (I).λ/4×0.80(=100)<nd(=109.21)<λ/4×1.00(=125)

2) The value nd (n2×d2) of the higher refractive index is 203.3 andsatisfies Expression (II).λ/2×0.75(=187.5)<nd(=203.3)<λ/2×0.95(=237.5)

3) The value of the lower refractive index satisfies Expression (III).λ/4×0.95(=118.75)<nd(=122.98)<λ/4×1.05(=131.25)

COMPARATIVE EXAMPLE 1

Physical vapor deposition was employed to form, on the hard coat layer46 of Example 1, a titanium oxide film (refractive index: 2.39, filmthickness: 25 nm) and a silicon oxide film (refractive index: 1.47, filmthickness: 25 nm). The two films practically served as an intermediaterefractive sub-layer. Then a titanium oxide film (film thickness: 46 nm)and a silicon oxide film (film thickness: 97 nm) were formed in thisorder by physical vapor deposition as a high refractive sub-layer and alow refractive sub-layer, respectively, thus obtaining an AR film.

The AR films of Example 1 and Comparative Example 1 were evaluated assuch.

An adaptor (ARV-474) was attached to a spectrophotometer (V-550, aproduct of Jasco Corporation) to measure the specular reflectivity at anexit angle of −5° when the incident angle is 5° in a wavelength range of380 to 780 nm. The results are shown in FIG. 8. At the same time, theaverage reflectivity in a wavelength range of 450 to 850 nm wascalculated to evaluate the anti-reflection property. Furthermore, L*, a*and b* values of CIE 1976 L*a*b* color space representing the color tintof light under regular reflection with respect to the incident light atan incident angle of 5° from a CIE standard light source was calculatedfrom the measured reflection spectrum to evaluate the color tint of thereflected light. The evaluation results are shown in Table 1.

TABLE 1 Average Color tint reflectivity (%) a*/b* Example 1 0.28 2/−6 Comparative Example 1 0.33 9/−10

As shown in Table 1, the average reflectivity in a wavelength range of450 to 850 nm is 0.28% for the AR film of Example 1 and 0.33% for the ARfilm of Comparative Example 1. Both AR films are thus low in averagereflectivity (0.4% or less) and are well capable of avoiding reflectionon the display screen. On the other hand, in terms of color tint, a* andb* values of the AR film in Comparative Example 1 are 9 and −10,respectively, which are outside a region Al in FIG. 9 (limited region inthe present invention), and the film has failed to meet the requirementwhereas the AR film of Example 1 satisfies the requirement since a* andb* values of the film are 2 and −6, respectively, thus falling within aregion A2 (a preferably limited region in the present invention), whichis inside the region A1 of FIG. 9.

The above results show that the AR film of Example 1 is successful inlowering the reflectivity and reducing the color tint at the same time,and has obtained a preferable reflection characteristic.

EXAMPLE 2

In Example 2, the AR film 16 of Example 1 was attached to a monochromeliquid crystal display device (LCD) for evaluation.

Using an adhesive material, the AR film 16 of Example 1 was adhered tothe front surface of a monochrome LCD currently used as a medical LCDmonitor (FC-2090, a product of EIZO NANAO CORPORATION, panel size:20.8″, number of pixels: QXGA=2048×1536, pixel size: 207 μm=123 ppi, anIPS (In-Plane Switching) display with each pixel having three monochromesub-pixels). The LCD has no anti-glare property.

A monochrome LCD to which the AR film of Example 1 was not adhered wasprepared as Comparative Example 2. The LCD of Comparative Example 2 was,in other words, an existent monochrome LCD which was mostly identical tothe LCD panel of Example 2 and had no anti-glare property but had thefront surface treated in a different manner. Prepared as ComparativeExample 3 was a monochrome LCD to which an AG film (surface roughness:Ra (arithmetic average height)=0.08 to 1.15 μm and Rz (maximumheight)=0.7 to 1.2 μm) having no AR property was adhered instead of anAR film. The Comparative Examples 2 and 3 was also evaluated forcomparison.

A CR image, a CT image, or other medical images were displayed on themedical LCD monitors of Example 2 and Comparative Examples 2 and 3 toevaluate through visual inspection, the medical images displayed forreflection of the surroundings, the color tint, imbalance between blackand white due to peripheral light, glare, the look of ‘double vision’,and the sharpness and vividness.

The evaluation results are shown in Table 2.

Reflection on the display screen was evaluated based on whether or notreflection light of an observer on the monitor screen was noticeable.When the reflection was ignorable, the monitor was marked with a circle(success) in Table 2. When the reflection was noticeable, the monitorwas marked with an X (failure). As to the evaluation of the color tint,a circle was given when reflected light had no color but neutral, and anX was given when the reflected light was colored. The imbalance betweenblack and white due to peripheral light was evaluated in three grades:the circle mark indicates that the screen does not look whitish (thereis no black area standing out); the triangular mark indicates that thescreen appears a little whitish; and the mark X means that the screendefinitely has a whitish appearance. A circle was given when no glarewas recognized, whereas an X was given when the screen was glaring. Inthe evaluation of the look of ‘double vision’, the circle mark was givenwhen the image did not have a ‘double vision’ look, and the X mark wasgiven when it did. The sharpness and vividness were evaluated in threegrades: a circle means that the image is not blurred at all and isvivid; a triangle means that the image is rather blurred; and an X meansthat the image is blurred and dull.

TABLE 2 Comparative Comparative Example 2 Example 2 Example 3 Reflection◯ X ◯ [Reflection of [Reflection [Reflection is obscured observer is ofobserver and therefore ignorable] is noticeable] ignorable] Color tint ◯◯ ◯ Imbalance ◯ ◯ Δ between black and white due to peripheral lightGlare ◯ ◯ X Look of ‘double ◯ ◯ X vision’ Sharpness and ◯ ◯ Δ vividnessSurface roughness Ra = 0.005 μm — Ra = 0.08 to 0.15 μm or less — Rz =0.7 to 1.2 μm Rz = 0.01 μm or less

The results in Table 2 shows that the LCD unit 14 (the polarizationplate 30, see FIG. 2) of Comparative example 2, which is an existentmedical LCD monitor, has a flat surface and is high in surfacereflectivity to reflect incident light as shown in FIG. 10B.Accordingly, the monitor of Comparative Example 2 is regarded well interms of the color tint, occurrence of whitish color due to peripherallight, glare, the look of ‘double vision’, and the sharpness andvividness while reflection light of an observer is clearly found on thescreen to the point of interfering with observation of a displayedimage. As to Comparative Example 3, Table 2 shows that the LCD unit 14(the polarization plate 30, see FIG. 2) has minute surfaceirregularities and incident light is irregularly reflected and scatteredas shown in FIG. 10C. This obscures reflection light of the observer,making the reflection ignorable. Also, reflected light is not coloredbut neutral. However, the monitor of Comparative Example 3 has a littlewhitish appearance caused by peripheral light, glaring and the ‘doublevision’ look are recognized, and the sharpness and vividness of adisplayed image is insufficient, thus blurring a displayed image andmaking interpretation of the image difficult.

In contrast, the surface reflectivity of the AR film 16 adhered to theLCD unit 14 (polarization plate 30) in Example 2 is as low as 0.4% orless, and reflection of incident light is reduced by the AR film 16 asshown in FIG. 10A. This makes reflection light of an observer ignorable.Also, reflected light is not colored but neutral. In addition, themonitor of Example 2 rates well in terms of occurrence of whitish colordue to peripheral light, glare, the look of ‘double vision’, and thesharpness and vividness, which gives the monitor an excellent reflectionperformance.

In conclusion, the medical LCD monitor of Example 2 is proved to be anexcellent medical display which can provide a clear, film-like imagethat does not make tired an observer interpreting for a long period oftime and therefore is suitable for diagnostic or like other uses.

Given above through various embodiments are detailed descriptions on amedical display of the present invention and a medical display systemusing the same. However, the present invention is not limited to theembodiments described above, and various improvement and modificationscan be made without departing from the gist of the present invention.

As described in detail above, according to the present invention, anexcellent medical display for diagnostic or other uses can be obtainedat low cost which is capable of displaying a clear, film-like,high-quality, diagnostic image that is free from reflection on thedisplay screen and coloring and that does not make tired an observerinterpreting for a long period of time by using, in a 100 to 300 ppihigh-definition matrix display, a high performance anti-reflection filmwhich is flat or has a given degree of flatness, in other words, whichdoes not have an anti-glare property, and which is successful inachieving lowering of specular reflectivity and reduction of color tintat the same time.

Also, according to the present invention, the luminance of an imagedisplayed on this medical display can be measured accurately, andtherefore the gradation can be corrected with precision to, for example,the gradation characteristic of GSDF by DICOM. This makes it possible toprovide a medical display system that is capable of stably displaying,as a diagnostic image, on the medical display, a clear, film-like,high-quality image that does not make tired an observer interpreting fora long period of time.

1. A medical display, comprising: a display device of a matrix typehaving a resolution of 100 to 300 ppi to display a medical image; and atleast one anti-reflection layer on a side of a front surface of saiddisplay device, wherein said anti-reflection layer has an averagespecular reflectivity of 0.5% or less at an incident angle of 5° in awavelength range of 450 to 650 nm, said anti-reflection layer receiveslight from a CIE standard light source D65 at an incident angle of 5° ina wavelength range of 380 to 780 nm to reflect the light as regularreflection light whose color falls within a range of −7≦a*≦7 and−10≦b*≦−10 in terms of a* and b* values of CIE 1976 L*a*b* color space,said anti-reflection layer is placed on a surface whose flatness isdefined by an arithmetic average height Ra and a maximum height Rzaccording to JIS B 0601-2001, with Ra set at 0.02 μm or less and Rz setat 0.04 μm or less, and said anti-reflection layer does not have ananti-glare property.
 2. The medical display according to claim 1,wherein said anti-reflection layer in a form of an anti-reflection filmis formed on a support.
 3. The medical display according to claim 2,wherein said anti-reflection film is spread over said front surface ofthe display device.
 4. The medical display according to claim 2, whereina protective panel is attached to said front surface of the displaydevice in a manner that puts a distance between said protective paneland said front surface of the display device to avoid contact, andwherein one of said anti-reflection film and said anti-reflection layeris placed on each side of said protective panel.
 5. The medical displayaccording to claim 1, wherein said anti-reflection layer is provided onsaid front surface of the display device.
 6. The medical displayaccording to claim 1, wherein said anti-reflection layer has suchcharacteristics that the a* value and the b* value fulfill 0≦a*≦5 and−7≦b*≦0, respectively, and that the average specular reflectivity is0.3% or less at the incident angle of 5° in the wavelength range of 450nm to 650 nm.
 7. The medical display according to claim 1, wherein asize of a display screen on said front surface of the display device is18″ to 23″.
 8. The medical display according to claim 1, wherein saiddisplay device is a monochrome display device.
 9. The medical displayaccording to claim 1, wherein a plane radiographic image obtained by CR(computed radiography) or using a flat panel sensor is displayed at aresolution of 100 to 180 ppi.
 10. The medical display according to claim1, wherein a mammographic image obtained by CR (computed radiography) orusing a flat panel sensor is displayed at a resolution of 180 to 300ppi.
 11. A medical display, comprising: a display device of a matrixtype having a resolution of 100 to 300 ppi to display a medical image;and at least one anti-reflection layer on a side of a front surface ofsaid display device, wherein said anti-reflection layer has an averagespecular reflectivity of 0.5% or less at an incident angle of 50° in awavelength range of 450 to 650 nm, said anti-reflection layer receiveslight from a CIE standard light source D65 at an incident angle of 5° ina wavelength range of 380 to 780 nm to reflect the light as regularreflection light whose color falls within a range of −7≦a*≦7 and−10≦b*≦10 in terms of a* and b* values of CIE 1976 L*a*b* color space,said anti-reflection layer is placed on a surface whose flatness isdefined by an arithmetic average height Ra and a maximum height Rzaccording to JIS B 0601-2001, with Ra set at 0.02 μm or less and Rz setat 0.04 μm or less, and said anti-reflection layer in a form of ananti-reflection film is formed on a support, wherein saidanti-reflection film has a transparent support having a refractive indexof nB, a hard coat layer having a refractive index of nH and beingplaced on the transparent support, and the anti-reflection layer beingplaced on the hard coat layer, wherein said anti-reflection layerpractically has three sub-layers of different refractive indexes, withan intermediate refractive sub-layer being closest to said transparentsupport and having a refractive index of n1, a high refractive sub-layerfollowing said intermediate refractive sub-layer and having a refractiveindex of n2, and a low refractive sub-layer being farthest to saidtransparent support and having a refractive index of n3, wherein therefractive indexes of said three sub-layers satisfy the followingrelations,n3<nB, nH<n1<n2 wherein, at a design wavelength λ (500 nm), saidintermediate refractive sub-layer, said high refractive sub-layer, andsaid low refractive sub-layer satisfy the following expressions (I),(II), and (III), respectively,λ/4×0.80<n1×d1<λ/4×1.00  (I)λ/2×0.75<n2×d2<λ/2×0.95  (II)λ/4×0.95<n3×d3<λ/4×1.05  (III) (where d1 represents a thickness (nm) ofthe intermediate refractive sub-layer, d2 represents a thickness (nm) ofthe high refractive sub-layer, and d3 represents a thickness (nm) of thelow refractive sub-layer.)
 12. A medical display system, comprising: amedical display displaying a medical image; and a luminance metermeasuring luminance, wherein said medical display, comprising: a displaydevice of a matrix type having a resolution of 100 to 300 ppi; and atleast one anti-reflection layer on a side of a front surface of saiddisplay device, wherein said anti-reflection layer has an averagespecular reflectivity of 0.5% or less at an incident angle of 5° in awavelength range of 450 to 650 nm, said anti-reflection layer receiveslight from a CIE standard light source D65 at an incident angle of 5° ina wavelength range of 380 to 780 nm to reflect the light as regularreflection light whose color falls within a range of −7≦a*≦7 and−10≦b*≦10 in terms of a* and b* values of CIE 1976 L*a*b* color space,and said anti-reflection layer is placed on a surface whose flatness isdefined by an arithmetic average height Ra and a maximum height Rzaccording to JIS B 0601-2001, with Ra set at 0.02 μm or less and Rz setat 0.04 μm or less, and wherein said medical display system has afunction of measuring surface reflection luminance when a power isturned off and display luminance when the power is turned on with saidluminance meter, a function of judging measurement data and displayingjudgment results, a function of saving the measurement data and thejudgment results, and a function of correcting gradation based on themeasurement data.
 13. The medical display system according to claim 12,wherein said luminance meter is connected online and has a function ofmeasuring the luminance in sync with display of a luminance measurementtest pattern on a display screen of said display device.